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  Rice Diseases

Sheath blight is the most prevalent rice disease in the state of Arkansas affecting at least 750,000 acres each year. It is worse on semi-dwarf long grain varieties, with most of these fields treated with fungicides. Read more about Sheath blight on pages 2-5. 

Green rice sheath with diseased brown patches on it.

Blast is a very important disease in certain areas each year and in favorable years can be devastating, causing up to 100% yield loss. The disease may affect leaves, stem nodes, collars, and panicles. It is managed using resistant varieties, water depth, planting date, and fungicides. Read more about Blast Rice Diseases on pages 1-2, 6-7. 

Rice blast symptoms on leavesRice blast symptoms on neck

Straighthead is a disorder of unknown cause. Symptoms can be induced with arsenic under artificial conditions. It is the oldest known rice disease in Arkansas, occurs on certain fields and can cause heavy losses approaching 100% if these fields are not drained and dried at the right timing. Some varieties are more susceptible than others. Read more abouStraighthead on page 12.

 
Photo of rice grains still on plant that are puffed up and dirty brown in color.

Kernel Smut has been an increasing problem for many years in Arkansas. Infected kernels turn to black powder inside causing quality problem, especially if the rice is used for parboiling. The disease is suppressed by reducing nitrogen fertilizer and applying fungicides containing propiconazole at the right rate and timing. Read more about Kernel Smut Rice Disease on pages 9-10. 

 Rice plant with black spots on the brownish yellow grain.

False smut was first reported in Arkansas in 1997 and has been widespread in all rice producing counties. Similar to kernel smut, false smut spores replace the developing rice kernel and greatly affect grain quality. It is more common in fields with high nitrogen rate and on later planted rice. It is managed using resistant varieties, adequate nitrogen rate and spraying fungicides containing propiconazole. Rate and timing are important. Read more about False Smut Rice Disease on pages 10-11. 

 
Photo of pale green rice plant with orange leaves.

Bacterial panicle blight has been a threatening problem for rice production in recent years in Arkansas. Most commercial cultivars are susceptible (S) or very susceptible (VS). Jupiter and the hybrids show moderate resistance level. A yield loss up to 50 percent can be caused in susceptible varieties that flower in late hot season. There are no recommended pesticides. Early planting and managing nitrogen fertilizer may reduce disease incidence and severity. Read more about Bacterial Panicle Blight on page 11Rice DiseaseEarly planting for BPB, FSA7580

Green rice plant with brown grain which is Bacterial panicle blight.

Autumn decline of Hydrogen sulfide toxicity (Akiochi) occurs in roots of rice that are grown on highly anaerobic flooded soils. Rice roots turn black and eventually die and rot. Some rice fields across the state of Arkansas suffer from this disorder. H2S odor is often noticed in affected fields. Draining fields at the right time to allow oxygen into soil enhances new root growth. Read more about Autumn decline or Hydrogen sulfide toxicity on page 13 ,  Akiochi. 

Roots of a rice plant that are brown and black in color.

Rice seedling rots and seedling diseases are consistent problems on much of the April planted rice in Arkansas and on certain minimum tillage fields. While reducing stand considerably, rice yields may be unaffected by seedling diseases if the stand is uniform, because modern rice varieties have the ability to tiller to fill available space and compensate for early stand loss. Read on seed rots and seedling diseases,  Managing seedling diseases
Rice seedlings that are green and brownish in color.

Other well known rice diseases are sporadic, localized or minor in the state. They include stem rot, black sheath rot, scald, scab, aggregate sheath spot, bordered sheath spot, leaf smut, brown spot and narrow brown spot among others.

In rare instances, any of these diseases have the potential to cause yield loss under ideal circumstances. White tip nematode is seed-borne and lives inside rice plant and feeds on developing leaf tissue resulting in distinctive whit tip on affected leaves.

Arkansas Rice Production Handbook - Disease Chapter _MP192 

Rice Seedling Fungicides

Rice Fungicides 

Plant Health Clinic

Sheath Blight and Blast Management in Arkansas

Image Library - Rice Diseases in Arkansas 

Arkansas Row Crops - Rice

Arkansas Rice Update

Links

Diseases of Rice – American Phytopathological Society

Missouri Rice Disease Control

Rice - How to Manage Pests - UC Pest Management Guidelines - University of California - Agriculture and Natural Resources

AG Chem Information Services for Growing Companies- Site that hosts pesticide labels, including fungicide labels

Greenbook- Site that hosts pesticide labels, including fungicide labels

Diagnosis of Common Diseases of Rice | Rice Knowledge Bank

Contact:

Yeshi Wamishe
Extension Plant Pathologist
University of Arkansas
Division of Agriculture
Cooperative Extension Service
Rice Research and Extension Center
2900 HWY 130 E. Stuttgart, AR 72160
Phone:Office 870-673-2661 Ex. 224
Mobile: 870-659-6864
Email: ywamishe@uaex.edu

 

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